The present invention relates to a gripper mechanism for a manipulator or the like in accordance with the preamble to claim 1.
Such a gripper mechanism is described in Federal Republic of Germany Patent 34 41 643.9. In that case, the gripper finger is guided as coupler of a six-member positive guide mechanism. The six-member guide mechanism consists of the combination of a special slider/crank mechanism, an equal-sided link quadrilateral, a special link quadrilateral, a link parallelogram in the manner that the slide of the slider/crank mechanism and the gripper finger together form two opposite links of the link quadrilateral. The slide link of the slider/crank mechanism and the drive of the gripper mechanism together form a single unit, the slide rod of the drive unit not carrying out any movement in the direction of the slide axis with respect to the gripper housing or frame.
In the invention according to Federal Republic of Germany Patent 34 41 643.9, the single slide rod of the centrally arranged drive unit serves as attachment member for the robot arm. This rod must extend through the movable cylinder and take up the entire lateral loads on the gripper, including the weight of the object as well as the dynamic transverse and torsional forces which are produced upon the transport and rotation of the object, and transmit them to the robot arm. In this way, this gripper mechanism is of very limited load-bearing capacity. It is torsionally and flexurally weak and, in the case of objects of greater weight, loses stability and precision of positioning.
Another gripper mechanism is known from EP 0 15 32 11. In that case, the gripper finger is guided on the frame as link of a six-member positive guide mechanism. The link of a link parallelogram which is opposite the gripper finger is driven by slide rod of a slide link which serves as actuating unit. In this connection, the gripper finger travels linearly up and down perpendicular to the slide axis along a guide plate which is fastened to the frame. In the case of the actuating unit, the slide rod is arranged centrally and movably and the cylinder is fixed on the frame.